Norlabdane oxide may be structurally shown as follows: ##STR1## Compound (1) is presently one of the most commercially important perfume components for providing ambergris-type odors. Ambergris is a metabolic product of sperm whales which has been used in the past as a valuable constituent of fine fragrances..sup.1 Natural ambergris itself is no longer used for this purpose. However, there is a demand for perfume ingredients with ambergris-type odors. Compound (1) represents one of the preferred synthetic compounds with desirable ambergris-type odor and is commercially available under various names (notably as Amberlyn, Ambroxan, Ambrox or Amberoxide)..sup.2
Since the first reported synthesis of compound (1),.sup.3 a number of synthesis procedures have been proposed. However, these are complex and laborious procedures which provide only a low yield of the desired product. Typically, these procedures include synthesis from sesqui- and diterpenoids..sup.4 More recently, it has been shown that naturally occurring (-)-sclareol.sup.5,6 or communic acid.sup.7,8 can be used as starting materials to prepare (1).
The reported procedures in going from the naturally occurring sclareol of structure (2): ##STR2## to the desired compound (1).sup.5,6, are, generally speaking, preferable to the communic acid pathways because the overall yields seem to be higher using (2), apparently due to a decrease in the number of steps required. In any case, all of the previously known methods using sclareol (2), as well as the current industrial process,.sup.1 lead to the formation of the diol (3): ##STR3## This must then be cyclized to give compound (1). This requires considerable care as the less desired, more thermodynamically stable iso-form of compound (1) may result.sup.9,10. This iso-form possesses inferior olfactive properties and serves to reduce the overall effectiveness of the synthesis process with respect to the production of compound (1).
In view of the foregoing, the principal object of the present invention is to provide a simplified but highly effective process for preparing compound (1) starting with sclareol. Other objects will also be hereinafter apparent.